U.S. patent application number 14/912864 was filed with the patent office on 2016-07-14 for hollow metal particles, electrode catalyst including same, electrochemical battery including the electrode catalyst, and method of manufacturing hollow metal particles.
The applicant listed for this patent is LG CHEM, LTD.. Invention is credited to Jun Yeon CHO, Gyo Hyun HWANG, Kwanghyun KIM, Sang Hoon KIM.
Application Number | 20160204448 14/912864 |
Document ID | / |
Family ID | 53199395 |
Filed Date | 2016-07-14 |
United States Patent
Application |
20160204448 |
Kind Code |
A1 |
KIM; Sang Hoon ; et
al. |
July 14, 2016 |
HOLLOW METAL PARTICLES, ELECTRODE CATALYST INCLUDING SAME,
ELECTROCHEMICAL BATTERY INCLUDING THE ELECTRODE CATALYST, AND
METHOD OF MANUFACTURING HOLLOW METAL PARTICLES
Abstract
The present specification relates to a hollow metal particle, an
electrode catalyst including the same, an electrochemical battery
including the electrode catalyst, and a method of manufacturing the
hollow metal particle.
Inventors: |
KIM; Sang Hoon; (Daejeon,
KR) ; HWANG; Gyo Hyun; (Daejeon, KR) ; CHO;
Jun Yeon; (Daejeon, KR) ; KIM; Kwanghyun;
(Daejeon, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LG CHEM, LTD. |
Seoul |
|
KR |
|
|
Family ID: |
53199395 |
Appl. No.: |
14/912864 |
Filed: |
November 28, 2014 |
PCT Filed: |
November 28, 2014 |
PCT NO: |
PCT/KR2014/011562 |
371 Date: |
February 18, 2016 |
Current U.S.
Class: |
429/524 ;
502/164; 502/326 |
Current CPC
Class: |
H01M 4/921 20130101;
B22F 1/0051 20130101; H01M 4/8657 20130101; B22F 9/24 20130101;
H01M 4/928 20130101; B22F 1/025 20130101; Y02E 60/50 20130101; H01M
2008/1095 20130101; H01M 4/8652 20130101 |
International
Class: |
H01M 4/92 20060101
H01M004/92; H01M 4/86 20060101 H01M004/86 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 28, 2013 |
KR |
10-2013-0146207 |
Claims
1. A hollow metal particle comprising: a hollow core portion; and a
metal shell including a first metal, a second metal, and a third
metal, wherein the second metal and the third metal each include a
metal having a standard reduction potential that is lower than a
standard reduction potential of the first metal.
2. The hollow metal particle of claim 1, wherein the metal shell is
formed of the first metal, the second metal, and the third
metal.
3. The hollow metal particle of claim 1, wherein the hollow core
portion includes a surfactant.
4. The hollow metal particle of claim 1, wherein the first metal
includes at least one of precious metal-based metals.
5. The hollow metal particle of claim 1, wherein the first metal
includes at least one of platinum (Pt), ruthenium (Ru), rhodium
(Rh), osmium (Os), iridium (Ir), palladium (Pd), gold (Au), and
silver (Ag).
6. The hollow metal particle of claim 4, wherein the second metal
and the third metal each include at least one of transition metals
having a standard reduction potential that is lower than a standard
reduction potential of the precious metal-based metals.
7. The hollow metal particle of claim 6, wherein the transition
metals having the standard reduction potential that is lower than
the standard reduction potential of the precious metal-based metals
include nickel (Ni), cobalt (Co), iron (Fe), and copper (Cu).
8. The hollow metal particle of claim 1, wherein when a sum of mole
numbers of the first metal, the second metal, and the third metal
is 1, a mole ratio of the first metal is 0.6 or more and 0.9 or
less.
9. The hollow metal particle of claim 1, wherein when a sum of mole
numbers of the first metal, the second metal, and the third metal
is 1, a mole ratio of a sum of the mole numbers of the second metal
and the third metal is 0.1 or more and 0.4 or less.
10. The hollow metal particle of claim 1, wherein the first metal,
the second metal, and the third metal are obtained by reducing a
first metal precursor, a second metal precursor, and a third metal
precursor, respectively, and a mole ratio of the first metal
precursor and the second metal precursor is 1:0.5 to 3.
11. The hollow metal particle of claim 1, wherein the first metal,
the second metal, and the third metal are obtained by reducing a
first metal precursor, a second metal precursor, and a third metal
precursor, respectively, and a mole ratio of the first metal
precursor and the third metal precursor is 1:0.5 to 3.
12. The hollow metal particle of claim 3, wherein the surfactant
includes two kinds or more.
13. The hollow metal particle of claim 3, wherein the surfactant
includes one kind or more cation surfactants and one kind or more
anion surfactants.
14. The hollow metal particle of claim 13, wherein a mole ratio of
the cation surfactants is 0.1 or more and 0.4 or less based on a
mole number of the anion surfactants.
15. The hollow metal particle of claim 1, wherein a size of the
hollow metal particle is 20 nm or less.
16. An electrode catalyst comprising: the hollow metal particle of
claim 1.
17. An electrochemical battery comprising: the electrode catalyst
of claim 16.
18. The electrochemical battery of claim 17, wherein the
electrochemical battery is a fuel cell.
19. A method of manufacturing a hollow metal particle, comprising:
forming a hollow core portion; and a metal shell including a first
metal, a second metal, and a third metal, wherein the second metal
and the third metal each include a metal having a standard
reduction potential that is lower than a standard reduction
potential of the first metal.
20. The method of claim 19, wherein the forming of the hollow core
portion and the metal shell includes forming the metal shell
including the first metal, the second metal, and the third metal on
a surface of a micelle formed of a surfactant.
21. The method of claim 20, wherein the forming of the the metal
shell on the surface of the micelle includes: agitating a solution
including the surfactant, a first metal precursor, a second metal
precursor, a third metal precursor, and a solvent; and adding a
reducing agent to the solution to reduce the first metal precursor,
the second metal precursor, and the third metal precursor.
22. The method of claim 21, wherein the solvent is water.
23. The method of claim 22, wherein in the solution, a
concentration of the surfactant is 0.5 times or more and 5 times or
less of a critical micelle concentration (CMC) to water.
24. The method of claim 21, wherein a mole ratio of the first metal
precursor and the second metal precursor is 1:0.5 to 3.
25. The method of claim 21, wherein a mole ratio of the first metal
precursor and the third metal precursor is 1:0.5 to 3.
Description
TECHNICAL FIELD
[0001] This application claims priority to and the benefit of
Korean Patent Application No. 10-2013-0146207 filed in the Korean
Intellectual Property Office on Nov. 28, 2013, the entire contents
of which are incorporated herein by reference.
[0002] The present specification relates to a hollow metal
particle, an electrode catalyst including the same, an
electrochemical battery including the electrode catalyst, and a
method of manufacturing the hollow metal particle.
BACKGROUND ART
[0003] Nano-particles are particles having a nano-scale particle
size, and exhibit a quantum confinement effect where energy
required for electron transference is changed according to a size
of a material, and optical, electric, and magnetic properties that
are entirely different from those of a material in a bulk state due
to a wide specific surface area. Accordingly, great interest has
focused on availability thereof in catalyst, electric and magnetic,
optical, and medical fields because of the aforementioned
properties. The nano-particles may be said to be an intermediate
between a bulk and a molecule, and can be synthesized in view of
approaching methods in two directions, that is, a "Top-down"
approaching method and a "Bottom-up" approaching method.
[0004] Examples of a method of synthesizing metal nano-particles
include a method of reducing metal ions on a solution by a reducing
agent, a method using a gamma ray, an electrochemical method, and
the like, but in the existing methods, since it is difficult to
synthesize nano-particles having a uniform size and shape or an
organic solvent is used, problems such as environmental pollution
and high costs occur, and thus it is difficult to perform mass
production economically. Therefore, there is a demand for
development of high-quality nano-particles having a uniform
size.
DETAILED DESCRIPTION OF THE INVENTION
Technical Problem
[0005] The present specification has been made in an effort to
provide a hollow metal particle, an electrode catalyst including
the same, an electrochemical battery including the electrode
catalyst, and a method of manufacturing the hollow metal
particle.
TECHNICAL SOLUTION
[0006] An exemplary embodiment of the present specification
provides a hollow metal particle including: a hollow core portion;
and a metal shell including a first metal, a second metal, and a
third metal, in which the second metal and the third metal each
include a metal having a standard reduction potential that is lower
than a standard reduction potential of the first metal.
[0007] Another exemplary embodiment of the present specification
provides an electrode catalyst including the hollow metal
particle.
[0008] Yet another exemplary embodiment of the present
specification provides an electrochemical battery including the
electrode catalyst.
[0009] Still another exemplary embodiment of the present
specification provides a method of manufacturing a hollow metal
particle, including: forming a hollow core portion; and a metal
shell including a first metal, a second metal, and a third metal,
in which the second metal and the third metal each include a metal
having a standard reduction potential that is lower than a standard
reduction potential of the first metal.
ADVANTAGEOUS EFFECTS
[0010] The present specification can provide particles having a
uniform size to apply the particles to various fields.
BRIEF DESCRIPTION OF DRAWINGS
[0011] FIG. 1 is a transmission electron microscopy (TEM) picture
of a hollow metal particle manufactured in Example 1.
[0012] FIG. 2 is a TEM picture of a hollow metal particle
manufactured in Example 2.
[0013] FIG. 3 is a TEM picture of a hollow metal particle
manufactured in Comparative Example 1.
[0014] FIG. 4 illustrates an analysis result of an atomic percent
of an element positioned along a line of an arrow in the hollow
metal particle of FIG. 1 by an EDS line profile.
[0015] FIG. 5 illustrates an analysis result of an atomic percent
of an element positioned along a line of an arrow in the hollow
metal particle of FIG. 3 by an EDS line profile.
Best Mode
[0016] Hereinafter, the present specification will be described in
detail.
[0017] The present specification provides a hollow metal particle
including a hollow core portion; and a metal shell including a
first metal, a second metal, and a third metal.
[0018] The hollow core portion may include a material where the
core portion of the hollow metal particle is hollow, or a material
other than a metal.
[0019] In the case where the hollow core portion includes the
material other than the metal, for example, a surfactant may be
included.
[0020] In the exemplary embodiment of the present specification,
the surfactant may include two kinds or more.
[0021] In the exemplary embodiment of the present specification,
two kinds or more surfactants may include two kinds or more of a
cation surfactant, an anion surfactant, and a non-ionic
surfactant.
[0022] In the case where the surfactant includes one kind or more
cation surfactants and one kind or more anion surfactants, a mole
ratio of the cation surfactant may be 0.1 or more and 0.4 or less
based on a mole number of the anion surfactant. In this case,
stability of a micelle generated by the surfactant is
increased.
[0023] The first metal may include at least one of precious
metal-based metals. Specifically, the first metal may include at
least one of platinum (Pt), ruthenium (Ru), rhodium (Rh), osmium
(Os), iridium (Ir), palladium (Pd), gold (Au), and silver (Ag). If
necessary, the first metal may include platinum.
[0024] The second metal and the third metal may each include at
least one of transition metals having a standard reduction
potential that is lower than that of the precious metal-based
metals.
[0025] In the case where the first metal includes platinum, the
second metal and the third metal may each include at least one of
the transition metals having the standard reduction potential that
is lower than that of platinum.
[0026] The transition metals having the standard reduction
potential that is lower than that of the precious metal-based
metals may include nickel (Ni), cobalt (Co), iron (Fe), copper
(Cu), and the like.
[0027] Nickel, cobalt, iron, and copper are a metal having high
oxygen reduction reactivity among the transition metals.
[0028] Oxygen reduction reactivity of a metal where at least one of
nickel, cobalt, iron, and copper is alloyed with at least one of
the precious metal-based metals may be higher than individual
oxygen reduction reactivity of the precious metal-based metals.
[0029] Oxygen reduction reactivity of the metal where at least one
of nickel, cobalt, iron, and copper is alloyed with at least one of
platinum, ruthenium, rhodium, osmium, iridium, palladium, gold, and
silver may be higher than individual oxygen reduction reactivity of
the precious metal-based metals such as platinum, ruthenium,
rhodium, osmium, iridium, palladium, gold, and silver.
[0030] Oxygen reduction reactivity of the metal where at least one
of nickel, cobalt, iron, and copper is alloyed with platinum may be
higher than individual oxygen reduction reactivity of platinum.
[0031] Oxygen reduction reactivity of the metal where two or more
of nickel, cobalt, iron, and copper are alloyed with platinum may
be higher than individual oxygen reduction reactivity of
platinum.
[0032] Oxygen reduction reactivity of the metal where two kinds of
metals of nickel, cobalt, iron, and copper are alloyed with
platinum may be higher than individual oxygen reduction reactivity
of platinum.
[0033] The second metal and the third metal may be each
independently nickel (Ni) or cobalt (Co).
[0034] When a sum of mole numbers of the first metal, the second
metal, and the third metal is 1, a mole ratio of the first metal
may be 0.6 or more and 0.9 or less.
[0035] When the sum of the mole numbers of the first metal, the
second metal, and the third metal is 1, a mole ratio of the sum of
the mole numbers of the second metal and the third metal may be 0.1
or more and 0.4 or less.
[0036] The first metal is obtained by reducing a first metal
precursor, the second metal is obtained by reducing a second metal
precursor, the third metal is obtained by reducing a third metal
precursor, and the mole ratio of the first metal precursor and the
second metal precursor may be 1:0.5 to 3. In this case, the hollow
particle is well generated.
[0037] The mole ratio of the first metal precursor and the third
metal precursor may be 1:0.5 to 3. In this case, the hollow
particle is well generated.
[0038] The metal shell of the present specification may be formed
of the first metal, the second metal, and the third metal. That is,
the metal shell may have a three component system metal, and the
hollow metal particle of the present specification may be a three
component system hollow metal particle formed of three kinds of
metals.
[0039] A size of the hollow metal particle may be 20 nm or
less.
[0040] An average of the sizes of the hollow metal particles may be
10 nm or less.
[0041] A deviation from the average of the sizes of the hollow
metal particles may be 3 nm or less. In this case, as compared to
an existing nano-particle, the hollow metal particles are small and
uniform and have an increased specific surface area, and thus may
exhibit excellent activity.
[0042] For example, the case where the average of the sizes of the
hollow metal particles is 10 nm and the deviation thereof is 3 nm
means that the hollow metal particles are distributed in size of 7
nm or more and 13 nm or less. The present specification provides an
electrode catalyst including the hollow metal particle.
[0043] The catalyst means a material that has an increase or
decrease effect of a reaction speed and can exist in an original
state after a reaction is finished.
[0044] In the present specification, the electrode catalyst may be
a positive catalyst increasing the reaction speed, and
specifically, may be a positive catalyst increasing a speed of an
oxidation or reduction reaction in a cell.
[0045] The electrode catalyst may be a fuel cell catalyst, and
specifically, may be a catalyst for an oxygen reduction reaction in
a fuel cell.
[0046] The present specification provides an electrochemical
battery including the electrode catalyst.
[0047] The electrochemical battery is a cell converting chemical
energy into electric energy through a chemical reaction of a
material, and a kind of the electrochemical battery is not
particularly limited as long as the electrochemical battery is a
cell converting chemical energy into electric energy.
[0048] The electrochemical battery may be any one of a primary
cell, a secondary cell, a storage cell, and the fuel cell.
[0049] The kind of the electrochemical battery including the
electrode catalyst is not particularly limited, but the
electrochemical battery may be the secondary cell or the fuel cell,
for example, a polymer electrolyte membrane fuel cell.
[0050] The present specification provides a method of manufacturing
a hollow metal particle, including forming a hollow core portion;
and a metal shell including a first metal, a second metal, and a
third metal.
[0051] The hollow core portion, the first metal, the second metal,
the third metal, the metal shell, and the surfactant as will be
described later are the same as those described in the hollow metal
particle.
[0052] In the exemplary embodiment of the present specification,
the forming of the hollow core portion and the metal shell may
include forming the metal shell including the first metal, the
second metal, and the third metal on a surface of a micelle formed
of a surfactant.
[0053] In the exemplary embodiment of the present specification,
the forming of the hollow core portion and the metal shell may
include forming the metal shell including the first metal, the
second metal, and the third metal on the surface of the micelle
formed of a surfactant; and washing the particle in which the
hollow core portion and the metal shell are formed after the metal
shell is formed.
[0054] In the washing, the particle may be washed by water or
alcohol.
[0055] In the exemplary embodiment of the present specification,
the method may further include, after the metal shell is formed,
removing the micelle.
[0056] In the exemplary embodiment of the present specification,
the forming of the metal shell on the surface of the micelle may
include stirring a solution including a surfactant, a first metal
precursor, a second metal precursor, a third metal precursor, and a
solvent; and adding a reducing agent to the solution to reduce the
first metal precursor, the second metal precursor, and the third
metal precursor.
[0057] The kinds of the first metal precursor, the second metal
precursor, and the third metal precursor are not limited, but the
first metal precursor is a salt including a first metal ion or an
atom group ion including the first metal ion and may serve to
provide the first metal. The second metal precursor is a salt
including a second metal ion or an atom group ion including the
second metal ion and may serve to provide the second metal.
Further, the third metal precursor is a salt including a third
metal ion or an atom group ion including the third metal ion and
may serve to provide the third metal.
[0058] In the exemplary embodiment of the present specification,
the solvent may be water.
[0059] In the exemplary embodiment of the present specification, in
the case where water is selected as the solvent, in the solution, a
concentration of the surfactant may be 0.5 times or more and 5
times or less of a critical micelle concentration (CMC) to
water.
[0060] If the concentration of the surfactant is less than 0.5
times of the critical micelle concentration, the concentration of
the surfactant adsorbed on a metal salt may be relatively reduced.
Accordingly, an amount of the surfactant forming the core may be
entirely reduced. Meanwhile, if the concentration of the surfactant
is more than 5 times of the critical micelle concentration, the
concentration of the surfactant is relatively increased, and thus
the surfactant forming the hollow core and the metal particle not
forming the hollow core may be mixed to be aggregated.
[0061] According to the exemplary embodiment of the present
specification, the size of the hollow metal particle may be
adjusted by a chain length of the surfactant forming the micelle.
Specifically, if the chain length of the surfactant is short, since
the size of the micelle is reduced, a hollow size is reduced, and
thus the size of the hollow metal particle may be reduced.
[0062] According to the exemplary embodiment of the present
specification, the number of carbon atoms of a chain of the
surfactant may be 16 or less. Specifically, the number of carbon
atoms of the chain may be 8 or more and 16 or less. Alternatively,
the number of carbon atoms of the chain may be 10 or more and 12 or
less.
[0063] In the exemplary embodiment of the present specification,
two kinds or more surfactants may be provided.
[0064] In the exemplary embodiment of the present specification,
two kinds or more surfactants may include two kinds or more of the
cation surfactant, the anion surfactant, and the non-ionic
surfactant.
[0065] In the case where the surfactant includes one kind or more
cation surfactants and one kind or more anion surfactants, the mole
ratio of the cation surfactant may be 0.1 or more and 0.4 or less
based on the mole number of the anion surfactant. In this case,
stability of the micelle generated by the surfactant is
increased.
[0066] The anion surfactant is not particularly limited, but for
example, the anion surfactant may be selected from the group
consisting of potassium laurate, triethanolamine stearate, ammonium
lauryl sulfate, lithium dodecyl sulfate, sodium lauryl sulfate,
sodium dodecyl sulfate, alkyl polyoxyethylene sulfate, sodium
alginate, dioctyl sodium sulfosuccinate, phosphatidyl glycerol,
phosphatidyl inositol, phosphatidyl serine, phosphatidic acid and a
salt thereof, glyceryl ester, sodium carboxymethylcellulose, bile
acid and a salt thereof, cholic acid, deoxycholic acid, glycocholic
acid, taurocholic acid, glycodeoxycholic acid, alkyl sulfonate,
aryl sulfonate, alkyl phosphate, alkyl phosphonate, stearic acid
and a salt thereof, calcium stearate, phosphate, dioctyl
sulfosuccinate, dialkylester of sodium sulfosuccinate,
phospholipid, and calcium carboxymethylcellulose.
[0067] The cation surfactant is not particularly limited, but for
example, the cation surfactant may be selected from the group
consisting of a quaternary ammonium compound, benzalkonium
chloride, cetyltrimethylammonium bromide, chitosan,
lauryldimethylbenzylammonium chloride, acyl carnitine
hydrochloride, alkylpyridinium halide, cetyl pyridinium chloride,
cationic lipid, polymethyl methacrylate trimethylammonium bromide,
a sulfonium compound, polyvinylpyrrolidone-2-dimethylaminoethyl
methacrylate dimethyl sulfate, hexadecyltrimethyl ammonium bromide,
a phosphonium compound, benzyl-di(2-chloroethyl)ethylammonium
bromide, coconut trimethyl ammonium chloride, coconut trimethyl
ammonium bromide, coconut methyl dihydroxyethyl ammonium chloride,
coconut methyl dihydroxyethyl ammonium bromide, decyl triethyl
ammonium chloride, decyl dimethyl hydroxyethyl ammonium chloride
bromide, C.sub.12-C.sub.15-dimethyl hydroxyethyl ammonium chloride,
C.sub.12-C.sub.15-dimethyl hydroxyethyl ammonium chloride bromide,
coconut dimethyl hydroxyethyl ammonium chloride, coconut dimethyl
hydroxyethyl ammonium bromide, myristyl trimethyl ammonium
methylsulfate, lauryl dimethyl benzyl ammonium chloride, lauryl
dimethyl benzyl ammonium bromide, lauryl dimethyl (ethenoxy) 4
ammonium chloride, lauryl dimethyl (ethenoxy) 4 ammonium bromide,
N-alkyl (C.sub.12- C.sub.18)dimethylbenzyl ammonium chloride,
N-alkyl (C.sub.14-C.sub.18)dimethyl-benzyl ammonium chloride,
N-tetradecyldimethylbenzyl ammonium chloride monohydrate, dimethyl
didecyl ammonium chloride, N-alkyl (C.sub.12-C.sub.14)dimethyl
1-naphthylmethyl ammonium chloride, a trimethylammonium halide
alkyl-trimethylammonium salt, a dialkyl-dimethylammonium salt,
lauryl trimethyl ammonium chloride, an ethoxylated
alkylamidoalkyldialkylammonium salt, an ethoxylated
trialkylammonium salt, dialkylbenzene dialkylammonium chloride,
N-didecyldimethyl ammonium chloride, N-tetradecyldimethylbenzyl
ammonium chloride monohydrate, N-alkyl(C.sub.12-C.sub.14) dimethyl
1-naphthylmethyl ammonium chloride, dodecyldimethylbenzyl ammonium
chloride, dialkyl benzenealkyl ammonium chloride, lauryl trimethyl
ammonium chloride, alkylbenzyl methyl ammonium chloride, alkyl
benzyl dimethyl ammonium bromide, C.sub.12 trimethyl ammonium
bromide, C.sub.15 trimethyl ammonium bromide, C.sub.17 trimethyl
ammonium bromide, dodecylbenzyl triethyl ammonium chloride,
polydiallyldimethylammonium chloride, dimethylammonium chloride,
alkyldimethylammonium halogenide, tricetylmethylammonium chloride,
decyltrimethylammonium bromide, dodecyltriethylammonium bromide,
tetradecyltrimethylammonium bromide, methyl trioctylammonium
chloride, POLYQUAT 10, tetrabutylammonium bromide,
benzyltrimethylammonium bromide, choline ester, benzalkonium
chloride, stearalkonium chloride, cetylpyridinium bromide,
cetylpyridinium chloride, a halide salt of quaternized
polyoxyethylalkylamine, "MIRAPOL" (polyquaternium-2), "Alkaquat"
(alkyldimethyl benzylammonium chloride, manufactured by Rhodia
S.A.), an alkylpyridinium salt, amine, an amine salt, an imide
azolinium salt, protonated quaternary acrylamide, a methylated
quaternary polymer, and cationic guar gum, benzalkonium chloride,
dodecyltrimethylammonium bromide, triethanolamine, and
poloxamine.
[0068] According to the exemplary embodiment of the present
specification, the size of the hollow metal particle may be
adjusted by adjusting a kind of a counter ion of the surfactant
forming the micelle. Specifically, as the size of the counter ion
of the surfactant is increased, bonding force with a head portion
of an external end of the surfactant may be weakened to increase
the size of a hollow, and thus the size of the hollow metal
particle may be increased.
[0069] According to the exemplary embodiment of the present
specification, in the case where the surfactant is the anionic
surfactant, the surfactant may include NH.sub.4.sup.+, K.sup.+,
Na.sup.+, or Li.sup.+ as the counter ion.
[0070] Specifically, in the order of the case where the counter ion
of the surfactant is NH.sub.4.sup.+, the case where the counter ion
of the surfactant is K.sup.+, the case where the counter ion of the
surfactant is Na.sup.+, and the case where the counter ion of the
surfactant is Li.sup.+, the size of the hollow nano-particle may be
reduced.
[0071] According to the exemplary embodiment of the present
specification, in the case where the surfactant is the cationic
surfactant, the surfactant may include I.sup.-, Br.sup.-, or
Cl.sup.- as the counter ion.
[0072] Specifically, in the order of the case where the counter ion
of the surfactant is I.sup.-, the case where the counter ion of the
surfactant is Br.sup.-, and the case where the counter ion of the
surfactant is Cl.sup.-, the size of the hollow nano-particle may be
reduced.
[0073] According to the exemplary embodiment of the present
specification, the size of the hollow metal particle may be
adjusted by adjusting the size of the head portion of the external
end of the surfactant forming the micelle. Moreover, in the case
where the size of the head portion of the surfactant formed on an
external surface of the micelle is large, repulsive force between
the head portions of the surfactant may be increased to increase
the hollow, and thus the size of the hollow metal particle may be
increased.
[0074] According to the exemplary embodiment of the present
specification, the size of the hollow metal particle may be
determined by complex action of the aforementioned elements.
[0075] According to the exemplary embodiment of the present
specification, the aforementioned manufacturing method may be
performed at room temperature. Specifically, the manufacturing
method may be performed at a temperature in the range of 4.degree.
C. or more and 35.degree. C. or less and more specifically
15.degree. C. or more and 28.degree. C. or less.
[0076] In the exemplary embodiment of the present specification,
the forming of the metal shell on the surface of the micelle may be
performed at room temperature, specifically the temperature in the
range of 4.degree. C. or more and 35.degree. C. or less, and more
specifically 15.degree. C. or more and 28.degree. C. or less. If an
organic solvent is used as the solvent, manufacturing should be
performed at a high temperature of more than 100.degree. C. In the
present specification, since manufacturing can be performed at room
temperature, the manufacturing method is simple, and thus there is
a merit in a process and a cost reduction effect is large.
[0077] In the exemplary embodiment of the present specification,
the forming of the metal shell on the surface of the micelle may be
performed for 30 minutes to 24 hours, more specifically 2 hours to
18 hours, and even more specifically 4 hours to 12 hours.
[0078] In the exemplary embodiment of the present specification,
the reducing may be performed at room temperature, specifically the
temperature in the range of 4.degree. C. or more and 35.degree. C.
or less, and more specifically 15.degree. C. or more and 28.degree.
C. or less.
[0079] In the present specification, since manufacturing can be
performed at room temperature, the manufacturing method is simple,
and thus there is a merit in a process and a cost reduction effect
is large.
[0080] The reducing may be performed by reacting the first metal
precursor, the second metal precursor, the third metal precursor,
and the reducing agent for a predetermined time, specifically 30
minutes to 24 hours, more specifically 2 hours to 18 hours, and
even more specifically 4 hours to 12 hours.
[0081] In the exemplary embodiment of the present specification,
the reducing agent is not particularly limited as long as the
reducing agent is a strong reducing agent having standard reduction
potential of -0.23 V or less and specifically -4 V or more and
-0.23 V or less and has reducing power capable of reducing
dissolved metal ions to precipitate the metal ions into metal
particles.
[0082] The reducing agent may be, for example, at least one
selected from the group consisting of NaBH.sub.4, NH.sub.2NH.sub.2,
LiAlH.sub.4, and LiBEt.sub.3H.
[0083] In the case where a weak reducing agent is used, since there
is difficulty in performing a continuous process because of a slow
reaction speed and requirement of subsequent heating of the
solution, there may be a problem in mass production, and
particularly, in the case where ethylene glycol that is a kind of
the weak reducing agent is used, productivity in a continuous
process is low due to a reduction in flow speed by a high
viscosity.
[0084] According to the exemplary embodiment of the present
specification, in the forming of the metal shell on the surface of
the micelle, the non-ionic surfactant may be further added. In the
exemplary embodiment of the present specification, the non-ionic
surfactant may be specifically selected from the group consisting
of polyoxyethylene fatty alcohol ether, polyoxyethylene sorbitan
fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene
alkyl ether, a polyoxyethylene castor oil derivative, sorbitan
ester, glyceryl ester, glycerol monostearate, polyethylene glycol,
polypropylene glycol, polypropylene glycol ester, cetyl alcohol,
cetostearyl alcohol, stearyl alcohol, aryl alkyl polyether alcohol,
a polyoxyethylenepolyoxypropylene copolymer, poloxamer, poloxamine,
methyl cellulose, hydroxy cellulose, hydroxymethyl cellulose,
hydroxyethyl cellulose, hydroxy propyl cellulose, hydroxy
propylmethyl cellulose, hydroxypropylmethyl cellulose phthalate,
amorphous cellulose, polysaccharides, starch, a starch derivative,
hydroxyethyl starch, polyvinyl alcohol, triethanolamine stearate,
amine oxide, dextran, glycerol, acacia gum, cholesterol,
tragacanth, and polyvinylpyrrolidone.
[0085] The non-ionic surfactant is adsorbed on the surface of the
shell to uniformly disperse the hollow metal particles formed in
the solution. Therefore, the non-ionic surfactant may prevent
precipitation by agglomeration of the hollow metal particles and
form the hollow metal particles in a uniform size.
[0086] According to the exemplary embodiment of the present
specification, in the forming of the metal shell on the surface of
the micelle, a stabilizer may be further added.
[0087] In the exemplary embodiment of the present specification,
the stabilizer may include one or two or more selected from the
group consisting of specifically disodium phosphate, dipotassium
phosphate, disodium citrate, trisodium citrate.
[0088] In the method of manufacturing the hollow metal particle
according to the present specification, a three component system
hollow metal particle having a nano size can be manufactured at
room temperature on an aqueous solution by using the
surfactant.
[0089] Hereinafter, the present specification will be specifically
described in detail through Examples.
EXAMPLE
Example 1
[0090] K.sub.2PtCl.sub.4 as the first metal precursor,
Ni(NO.sub.3).sub.2 as the second metal precursor,
Co(NO.sub.3).sub.2 as the third metal precursor, trisodium citrate
as the stabilizer, lithium dodecylsulfate (LiDS) as the anion
surfactant, and dodecyltriethylammonium bromide (DTAB) as the
cation surfactant were dissolved in water, and then stirred. In
this case, the mole ratio of the first metal precursor, the second
metal precursor, and the third metal precursor was 1:1.5:1.5, and
LiDS was added at the concentration that was two times of the
critical micelle concentration (CMC) to water. After agitation for
30 minutes, NaBH.sub.4 that was the reducing agent was added to
perform the reaction for 4 hours or more. If the reaction was
finished, centrifugation was performed, and washing by water and
ethanol was performed to obtain the hollow metal particle.
[0091] In this case, the average size of the hollow metal particles
was 10 nm.
Example 2
[0092] In Example 1, the metal precursor was the same, LiDS was
added at the concentration that was seven time of the CMC, and the
reducing agent was added to perform the reaction.
Comparative Example 1
[0093] K.sub.2PtCl.sub.4 as the first metal precursor,
Ni(NO.sub.3).sub.2 as the second metal precursor, trisodium citrate
as the stabilizer, lithium dodecylsulfate (LiDS) as the anion
surfactant, and dodecyltriethylammonium bromide (DTAB) as the
cation surfactant were dissolved in water, and then stirred. In
this case, the mole ratio of the first metal precursor and the
second metal precursor was 1:3, and LiDS was added at the
concentration that was two times of the critical micelle
concentration (CMC) to water. After stirring for 30 minutes,
NaBH.sub.4 that was the reducing agent was added to perform the
reaction for 4 hours or more. If the reaction was finished,
centrifugation was performed, and washing by water and ethanol was
performed to obtain the hollow metal particle.
[0094] In this case, the average size of the hollow metal particles
was 10 nm.
[0095] [Measurement of transmission electron microscopy (TEM)]
[0096] A TEM picture of the hollow metal particle manufactured in
Example 1 is illustrated in FIG. 1, a TEM picture of the hollow
metal particle manufactured in Example 2 is illustrated in FIG. 2,
and a TEM picture of the hollow metal particle manufactured in
Comparative Example 1 is illustrated in FIG. 3.
[0097] [Measurement of energy dispersive spectroscopy (EDS)]
[0098] An analysis result of an atomic percent of an element
positioned along a line of an arrow in the hollow metal particle of
FIG. 1 by an EDS line profile is illustrated in FIG. 4.
[0099] An analysis result of an atomic percent of an element
positioned along a line of an arrow in the hollow metal particle of
FIG. 3 by an EDS line profile is illustrated in FIG. 5.
[0100] FIG. 4 illustrates a relative content of an atom along the
line represented by the arrow with respect to one of the hollow
metal particles of FIG. 1 in an EDS line profile form, and Pt that
is a main component is largely illustrated in a shell portion and
is illustrated in small in a central portion that is a hollow.
[0101] FIG. 5 illustrates a relative content of an atom along the
line represented by the arrow with respect to one of the hollow
metal particles of FIG. 3 in an EDS line profile form, and Pt that
is a main component is largely illustrated in a shell portion and
is illustrated in small in a central portion that is a hollow.
[0102] [Measurement of performance of fuel cell]
[0103] After the particles prepared in Example 1 and Comparative
Example 1 were each supported in carbon (Vulcan XC-72), single cell
performance of the fuel cell was evaluated under the following
condition.
[0104] Cell temp: 75.degree. C.
[0105] Anode: 100% RH H.sub.2 150 ccm
[0106] Cathode: 100% RH Air 500 ccm
[0107] Cell area: 5 cm.sup.2
[0108] As a result, carbon in which the three component system
hollow metal particles prepared in Example 1 were supported had
activity of 0.90 A/cm.sup.2 @0.6 V, and carbon in which the two
component system hollow metal particles prepared in Comparative
Example 1 were supported had activity of 0.81 A/cm.sup.2 @0.6
V.
* * * * *